/*
 * FreeRTOS Kernel V10.4.6
 * Copyright (C) 2021 Amazon.com, Inc. or its affiliates.    All Rights Reserved.
 *
 * SPDX-License-Identifier: MIT
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of
 * this software and associated documentation files (the "Software"), to deal in
 * the Software without restriction, including without limitation the rights to
 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
 * the Software, and to permit persons to whom the Software is furnished to do so,
 * subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
 * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
 * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
 * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 * https://www.FreeRTOS.org
 * https://github.com/FreeRTOS
 *
 */

#include "FreeRTOS.h"
#include "task.h"
#include "croutine.h"

/* Remove the whole file is co-routines are not being used. */
#if ( configUSE_CO_ROUTINES != 0 )

/*
 * Some kernel aware debuggers require data to be viewed to be global, rather
 * than file scope.
 */
        #ifdef portREMOVE_STATIC_QUALIFIER
                #define static
        #endif


/* Lists for ready and blocked co-routines. --------------------*/
        static List_t pxReadyCoRoutineLists[ configMAX_CO_ROUTINE_PRIORITIES ]; /*< Prioritised ready co-routines. */
        static List_t xDelayedCoRoutineList1;                                                                     /*< Delayed co-routines. */
        static List_t xDelayedCoRoutineList2;                                                                     /*< Delayed co-routines (two lists are used - one for delays that have overflowed the current tick count. */
        static List_t * pxDelayedCoRoutineList = NULL;                                                    /*< Points to the delayed co-routine list currently being used. */
        static List_t * pxOverflowDelayedCoRoutineList = NULL;                                    /*< Points to the delayed co-routine list currently being used to hold co-routines that have overflowed the current tick count. */
        static List_t xPendingReadyCoRoutineList;                                                             /*< Holds co-routines that have been readied by an external event.    They cannot be added directly to the ready lists as the ready lists cannot be accessed by interrupts. */

/* Other file private variables. --------------------------------*/
        CRCB_t * pxCurrentCoRoutine = NULL;
        static UBaseType_t uxTopCoRoutineReadyPriority = 0;
        static TickType_t xCoRoutineTickCount = 0, xLastTickCount = 0, xPassedTicks = 0;

/* The initial state of the co-routine when it is created. */
        #define corINITIAL_STATE        ( 0 )

/*
 * Place the co-routine represented by pxCRCB into the appropriate ready queue
 * for the priority.    It is inserted at the end of the list.
 *
 * This macro accesses the co-routine ready lists and therefore must not be
 * used from within an ISR.
 */
        #define prvAddCoRoutineToReadyQueue( pxCRCB )                                                                                                                                             \
        {                                                                                                                                                                                                                                     \
                if( pxCRCB->uxPriority > uxTopCoRoutineReadyPriority )                                                                                                                    \
                {                                                                                                                                                                                                                             \
                        uxTopCoRoutineReadyPriority = pxCRCB->uxPriority;                                                                                                                     \
                }                                                                                                                                                                                                                             \
                vListInsertEnd( ( List_t * ) &( pxReadyCoRoutineLists[ pxCRCB->uxPriority ] ), &( pxCRCB->xGenericListItem ) ); \
        }

/*
 * Utility to ready all the lists used by the scheduler.    This is called
 * automatically upon the creation of the first co-routine.
 */
        static void prvInitialiseCoRoutineLists( void );

/*
 * Co-routines that are readied by an interrupt cannot be placed directly into
 * the ready lists (there is no mutual exclusion).    Instead they are placed in
 * in the pending ready list in order that they can later be moved to the ready
 * list by the co-routine scheduler.
 */
        static void prvCheckPendingReadyList( void );

/*
 * Macro that looks at the list of co-routines that are currently delayed to
 * see if any require waking.
 *
 * Co-routines are stored in the queue in the order of their wake time -
 * meaning once one co-routine has been found whose timer has not expired
 * we need not look any further down the list.
 */
        static void prvCheckDelayedList( void );

/*-----------------------------------------------------------*/

        BaseType_t xCoRoutineCreate( crCOROUTINE_CODE pxCoRoutineCode,
                                                                 UBaseType_t uxPriority,
                                                                 UBaseType_t uxIndex )
        {
                BaseType_t xReturn;
                CRCB_t * pxCoRoutine;

                /* Allocate the memory that will store the co-routine control block. */
                pxCoRoutine = ( CRCB_t * ) pvPortMalloc( sizeof( CRCB_t ) );

                if( pxCoRoutine )
                {
                        /* If pxCurrentCoRoutine is NULL then this is the first co-routine to
                        * be created and the co-routine data structures need initialising. */
                        if( pxCurrentCoRoutine == NULL )
                        {
                                pxCurrentCoRoutine = pxCoRoutine;
                                prvInitialiseCoRoutineLists();
                        }

                        /* Check the priority is within limits. */
                        if( uxPriority >= configMAX_CO_ROUTINE_PRIORITIES )
                        {
                                uxPriority = configMAX_CO_ROUTINE_PRIORITIES - 1;
                        }

                        /* Fill out the co-routine control block from the function parameters. */
                        pxCoRoutine->uxState = corINITIAL_STATE;
                        pxCoRoutine->uxPriority = uxPriority;
                        pxCoRoutine->uxIndex = uxIndex;
                        pxCoRoutine->pxCoRoutineFunction = pxCoRoutineCode;

                        /* Initialise all the other co-routine control block parameters. */
                        vListInitialiseItem( &( pxCoRoutine->xGenericListItem ) );
                        vListInitialiseItem( &( pxCoRoutine->xEventListItem ) );

                        /* Set the co-routine control block as a link back from the ListItem_t.
                         * This is so we can get back to the containing CRCB from a generic item
                         * in a list. */
                        listSET_LIST_ITEM_OWNER( &( pxCoRoutine->xGenericListItem ), pxCoRoutine );
                        listSET_LIST_ITEM_OWNER( &( pxCoRoutine->xEventListItem ), pxCoRoutine );

                        /* Event lists are always in priority order. */
                        listSET_LIST_ITEM_VALUE( &( pxCoRoutine->xEventListItem ), ( ( TickType_t ) configMAX_CO_ROUTINE_PRIORITIES - ( TickType_t ) uxPriority ) );

                        /* Now the co-routine has been initialised it can be added to the ready
                         * list at the correct priority. */
                        prvAddCoRoutineToReadyQueue( pxCoRoutine );

                        xReturn = pdPASS;
                }
                else
                {
                        xReturn = errCOULD_NOT_ALLOCATE_REQUIRED_MEMORY;
                }

                return xReturn;
        }
/*-----------------------------------------------------------*/

        void vCoRoutineAddToDelayedList( TickType_t xTicksToDelay,
                                                                         List_t * pxEventList )
        {
                TickType_t xTimeToWake;

                /* Calculate the time to wake - this may overflow but this is
                 * not a problem. */
                xTimeToWake = xCoRoutineTickCount + xTicksToDelay;

                /* We must remove ourselves from the ready list before adding
                 * ourselves to the blocked list as the same list item is used for
                 * both lists. */
                ( void ) uxListRemove( ( ListItem_t * ) &( pxCurrentCoRoutine->xGenericListItem ) );

                /* The list item will be inserted in wake time order. */
                listSET_LIST_ITEM_VALUE( &( pxCurrentCoRoutine->xGenericListItem ), xTimeToWake );

                if( xTimeToWake < xCoRoutineTickCount )
                {
                        /* Wake time has overflowed.    Place this item in the
                         * overflow list. */
                        vListInsert( ( List_t * ) pxOverflowDelayedCoRoutineList, ( ListItem_t * ) &( pxCurrentCoRoutine->xGenericListItem ) );
                }
                else
                {
                        /* The wake time has not overflowed, so we can use the
                         * current block list. */
                        vListInsert( ( List_t * ) pxDelayedCoRoutineList, ( ListItem_t * ) &( pxCurrentCoRoutine->xGenericListItem ) );
                }

                if( pxEventList )
                {
                        /* Also add the co-routine to an event list.    If this is done then the
                         * function must be called with interrupts disabled. */
                        vListInsert( pxEventList, &( pxCurrentCoRoutine->xEventListItem ) );
                }
        }
/*-----------------------------------------------------------*/

        static void prvCheckPendingReadyList( void )
        {
                /* Are there any co-routines waiting to get moved to the ready list?    These
                 * are co-routines that have been readied by an ISR.    The ISR cannot access
                 * the ready lists itself. */
                while( listLIST_IS_EMPTY( &xPendingReadyCoRoutineList ) == pdFALSE )
                {
                        CRCB_t * pxUnblockedCRCB;

                        /* The pending ready list can be accessed by an ISR. */
                        portDISABLE_INTERRUPTS();
                        {
                                pxUnblockedCRCB = ( CRCB_t * ) listGET_OWNER_OF_HEAD_ENTRY( ( &xPendingReadyCoRoutineList ) );
                                ( void ) uxListRemove( &( pxUnblockedCRCB->xEventListItem ) );
                        }
                        portENABLE_INTERRUPTS();

                        ( void ) uxListRemove( &( pxUnblockedCRCB->xGenericListItem ) );
                        prvAddCoRoutineToReadyQueue( pxUnblockedCRCB );
                }
        }
/*-----------------------------------------------------------*/

        static void prvCheckDelayedList( void )
        {
                CRCB_t * pxCRCB;

                xPassedTicks = xTaskGetTickCount() - xLastTickCount;

                while( xPassedTicks )
                {
                        xCoRoutineTickCount++;
                        xPassedTicks--;

                        /* If the tick count has overflowed we need to swap the ready lists. */
                        if( xCoRoutineTickCount == 0 )
                        {
                                List_t * pxTemp;

                                /* Tick count has overflowed so we need to swap the delay lists.    If there are
                                 * any items in pxDelayedCoRoutineList here then there is an error! */
                                pxTemp = pxDelayedCoRoutineList;
                                pxDelayedCoRoutineList = pxOverflowDelayedCoRoutineList;
                                pxOverflowDelayedCoRoutineList = pxTemp;
                        }

                        /* See if this tick has made a timeout expire. */
                        while( listLIST_IS_EMPTY( pxDelayedCoRoutineList ) == pdFALSE )
                        {
                                pxCRCB = ( CRCB_t * ) listGET_OWNER_OF_HEAD_ENTRY( pxDelayedCoRoutineList );

                                if( xCoRoutineTickCount < listGET_LIST_ITEM_VALUE( &( pxCRCB->xGenericListItem ) ) )
                                {
                                        /* Timeout not yet expired. */
                                        break;
                                }

                                portDISABLE_INTERRUPTS();
                                {
                                        /* The event could have occurred just before this critical
                                         *    section.    If this is the case then the generic list item will
                                         *    have been moved to the pending ready list and the following
                                         *    line is still valid.    Also the pvContainer parameter will have
                                         *    been set to NULL so the following lines are also valid. */
                                        ( void ) uxListRemove( &( pxCRCB->xGenericListItem ) );

                                        /* Is the co-routine waiting on an event also? */
                                        if( pxCRCB->xEventListItem.pxContainer )
                                        {
                                                ( void ) uxListRemove( &( pxCRCB->xEventListItem ) );
                                        }
                                }
                                portENABLE_INTERRUPTS();

                                prvAddCoRoutineToReadyQueue( pxCRCB );
                        }
                }

                xLastTickCount = xCoRoutineTickCount;
        }
/*-----------------------------------------------------------*/

        void vCoRoutineSchedule( void )
        {
                /* Only run a co-routine after prvInitialiseCoRoutineLists() has been
                 * called.    prvInitialiseCoRoutineLists() is called automatically when a
                 * co-routine is created. */
                if( pxDelayedCoRoutineList != NULL )
                {
                        /* See if any co-routines readied by events need moving to the ready lists. */
                        prvCheckPendingReadyList();

                        /* See if any delayed co-routines have timed out. */
                        prvCheckDelayedList();

                        /* Find the highest priority queue that contains ready co-routines. */
                        while( listLIST_IS_EMPTY( &( pxReadyCoRoutineLists[ uxTopCoRoutineReadyPriority ] ) ) )
                        {
                                if( uxTopCoRoutineReadyPriority == 0 )
                                {
                                        /* No more co-routines to check. */
                                        return;
                                }

                                --uxTopCoRoutineReadyPriority;
                        }

                        /* listGET_OWNER_OF_NEXT_ENTRY walks through the list, so the co-routines
                         * of the same priority get an equal share of the processor time. */
                        listGET_OWNER_OF_NEXT_ENTRY( pxCurrentCoRoutine, &( pxReadyCoRoutineLists[ uxTopCoRoutineReadyPriority ] ) );

                        /* Call the co-routine. */
                        ( pxCurrentCoRoutine->pxCoRoutineFunction )( pxCurrentCoRoutine, pxCurrentCoRoutine->uxIndex );
                }
        }
/*-----------------------------------------------------------*/

        static void prvInitialiseCoRoutineLists( void )
        {
                UBaseType_t uxPriority;

                for( uxPriority = 0; uxPriority < configMAX_CO_ROUTINE_PRIORITIES; uxPriority++ )
                {
                        vListInitialise( ( List_t * ) &( pxReadyCoRoutineLists[ uxPriority ] ) );
                }

                vListInitialise( ( List_t * ) &xDelayedCoRoutineList1 );
                vListInitialise( ( List_t * ) &xDelayedCoRoutineList2 );
                vListInitialise( ( List_t * ) &xPendingReadyCoRoutineList );

                /* Start with pxDelayedCoRoutineList using list1 and the
                 * pxOverflowDelayedCoRoutineList using list2. */
                pxDelayedCoRoutineList = &xDelayedCoRoutineList1;
                pxOverflowDelayedCoRoutineList = &xDelayedCoRoutineList2;
        }
/*-----------------------------------------------------------*/

        BaseType_t xCoRoutineRemoveFromEventList( const List_t * pxEventList )
        {
                CRCB_t * pxUnblockedCRCB;
                BaseType_t xReturn;

                /* This function is called from within an interrupt.    It can only access
                 * event lists and the pending ready list.    This function assumes that a
                 * check has already been made to ensure pxEventList is not empty. */
                pxUnblockedCRCB = ( CRCB_t * ) listGET_OWNER_OF_HEAD_ENTRY( pxEventList );
                ( void ) uxListRemove( &( pxUnblockedCRCB->xEventListItem ) );
                vListInsertEnd( ( List_t * ) &( xPendingReadyCoRoutineList ), &( pxUnblockedCRCB->xEventListItem ) );

                if( pxUnblockedCRCB->uxPriority >= pxCurrentCoRoutine->uxPriority )
                {
                        xReturn = pdTRUE;
                }
                else
                {
                        xReturn = pdFALSE;
                }

                return xReturn;
        }

#endif /* configUSE_CO_ROUTINES == 0 */
